1. Field of the Invention
The present invention relates to a clamp for a flexible pipe.
More particularly, the present invention relates to a clamp for a flexible pipe to provide a load bearing flange on the flexible pipe permitting buoyancy jackets to be joined thereto.
2. Description of Related Art
In operations involving subsea gas and oil production, there is provided a flexible pipe or umbilical, referred to as a riser, which is used to convey product, power and communications between seabed assets and the surface. The risers require a certain strength and rigidity but must also remain flexible to offset the effects of currents in the sea. As such, the risers are normally provided in the form of a multilayered product including an outer thermoplastic sleeve surrounding an internal webbing of armor steel wire. One resultant drawback is that the risers are rather heavy and place a large amount of tension on its support.
The weight of the riser can be offset by joining buoyancy jackets to the riser at selected locations. In order to prevent the buoyancy jackets from sliding upwards along the riser, clamps are attached to the riser at selected locations and the buoyancy jackets are wrapped around the clamps. It is further preferable that the clamps are able to exert sufficient force onto the riser to frictionally prevent slippage of the riser's thermoplastic sleeve over its internal webbing.
Known types of clamps consist of a few bulky C-shaped bodies forming a cylindrical aperture having an internal diameter corresponding to the external diameter of the riser, and which may be joined to each other along one side by a hinge. In use, the C-shaped bodies are positioned to encircle the riser and then clamped to the riser, either by bolting the free ends of the clamp together or by surrounding the C-shaped bodies with a compression band that is tightened.
One disadvantage of using such bulky C-shaped bodies in a clamp is that the clamp is not easily adaptable for use on risers having different diameters. Also, the clamps are relatively heavy and difficult to manufacture due to the bulkiness of the C-shaped bodies.
These above-mentioned disadvantages have been at least partially overcome by forming the clamp from a plurality of relatively small elements, which are arranged in a radial array surrounding the riser and are supported and joined together by the compression band. However, it has been found that such an array clamp can be difficult to handle due to a lack of structural definition when it is in a rest, i.e. before being mounted onto the riser, resulting from the inherent flexibility within the compression band.
It is an object of the invention to suggest a clamp for a flexible pipe, which will assist in at least partially overcoming these problems.